After last week’s string of remarkable shake-ups at Apple, Google and Hewlett-Packard, I found myself thinking about what these three dramas tell us about the role of company founders.

In startup-crazed Silicon Valley, we have a romantic attachment to founders. They are risk takers, pioneers and innovators. We imbue founders with heroic qualities. At the same time there’s a strain of thinking that says: Founders don’t make good CEOs.

But I would argue that the best companies are run by their founders. And much of last week’s tumult convinced me of that.

But don’t take it just from me. Ben Horowitz, co-founder of the Andreessen Horowitz venture capital fund, said his firm would prefer to invest in companies run by founders. “The conventional wisdom says a startup CEO should make way for a professional CEO” once the company’s product has some momentum, Horowitz wrote. “We prefer to fund companies whose founder will run the company as its CEO.”

As evidence, he cited Amazon and Jeff Bezos; Microsoft and Bill Gates; and Oracle and Larry Ellison. Among the new crop of blockbuster startups, he listed Facebook and Mark Zuckerberg, as well as Zynga and Mark Pincus.

Horowitz also cited a recent study by researchers at the Wharton School of Business that examined 50 tech companies that either had an initial public offering or had been acquired. The researchers concluded, he said, that founding CEOs consistently did better than professional CEOs in managing their companies.

That brings me back to last week. The shake-ups at Apple, Google and HP were entirely unrelated, a fluke of timing. But they illustrate the importance of the role of founders.

Let’s start with Apple. This may be the best case for the virtues of the founder-run company. Steve Jobs started Apple and then was famously ousted, leading to a long period of decline and near-death for the company. He returned and restored its sense of passion and focus on innovation in what stands as one of the most remarkable business comeback stories of our time.

His medical leave also illustrates why founders with the right combination of business and technological skills can play such a critical role. Certainly Chief Operating Officer Tim Cook has shown he can ably run the company in a temporary capacity. But there are real concerns about his chances to maintain Apple’s high level of success over the long run.

At Google, we are about to see this hypothesis about founders get a serious run for its money. Co-founder Larry Page will take over later this spring as CEO just as Google confronts a number of tough challenges. As I wrote last week, his leadership will be tested quickly and intensively. But Google clearly felt tapping a founder for the job was the best thing to do, and it was probably smarter to do that than reach outside the company.

At HP, well, the valley’s most dysfunctional large company is decades removed from its days of being run by David Packard. There was a long period of decline, followed by recent years of success under two different CEOs who managed to turn HP into the world’s largest technology company despite an ongoing series of internal battles and scandals.

Yet it’s easy to argue that all of its boardroom drama would not have occurred under the guidance of one of the company’s founders. And I don’t think anyone believes that HP is home to a motivated, passionate set of employees who are united in a higher purpose, which is a critical element of long-term success.

The track record of the founder-CEO is certainly not perfect. Think Jerry Yang and Yahoo. And I was never convinced that Twitter co-founder Ev Williams, who stepped aside as CEO last year, was the right person to fix its reliability problems and sniff out a revenue model.

Still, the shake-ups this week remind me that there is a reason we hold founders in such high regard. It’s not just our emotional attachment to their stories. It’s not that companies can’t win without them. But in an era of constant disruption, their passion, focus and inspiration can be the difference between success and failure.